Battle-plan for CTFE

[MakersF via Digitalmars-d-announce]

On Wednesday, 26 October 2016 at 15:02:28 UTC, Stefam Koch wrote:
> Who can guess what this code does ?
>
>
> char[] obfuscatedFn(string a, string b, uint aLength = 0, uint 
> bLength = 0, uint cLength = 0, uint pos = 0, uint bPos = 0, 
> char[] result = [])
> {
>     aLength = cast(uint)a.length;
>     bLength = cast(uint)a.length;
>     cLength = aLength + bLength;
>     result.length = cLength;
>     while(aLength--)
>     {
>         result[pos] = a[pos];
>         ++pos;
>     }
>     while(bLength--)
>     {
>         result[pos] = b[bPos++];
>         ++pos;
>     }
>
>     return result;
> }

Shouldn't
> cLength = aLength + bLength;

actually be
> cLength = aLength + bLength + pos;
?
Otherwise when pos is > 0 it writes past the end of result.

Same problem in the first and second loop, where the legths 
should probably be

>     aLength = cast(uint)a.length - pos;
>     bLength = cast(uint)a.length - bPos;

If you fix the a and b Length then cLength is fine.

Or am I missing something?